In many industrial sectors it is necessary to transform reels of web material of one size into spools of a different size, by means of a process of un-winding parent reels, or so-called jumbo reels, and rewinding them into spools with different size characteristics. In some cases the web material from a single parent reel is unwound and divided into longitudinal strips, each of which is wound onto a helically wound spool. The finished spools obtained in this way are used as semi-finished products to feed production lines for other articles.
Machines that produce spools of helically wound web material from parent reels are sometimes called spooling machines. The web material can, for example, be a non-woven fabric. The helically wound spools that are obtained are used, for example, to feed machines for the production of sanitary towels, diapers and other hygienic and sanitary articles. The web material wound on the parent reels sometimes has a transversal size (corresponding to the axial dimension of the parent reel) 5-15 times the width of the individual longitudinal strips that are obtained by longitudinal cutting of the web material on the parent reels. The individual strips are fed simultaneously to helical winding stations, in each of which a helically wound spool is formed. The winding stations are arranged in line one after the other in a machine direction, defined by the direction of advance of the longitudinal strips obtained by cutting the material from the parent reels. Each strip is fed to the respective winding station along a feed path.
When a helically wound spool has been completed, the longitudinal strip must be severed, the completed helically wound spool must be removed from the respective winding station and replaced with a new winding core, to which the leading edge of the strip must be anchored to start winding of the next spool.
WO-A-2015/140466 describes a helical winding station in a spooling machine with a system to generate a perforation in the longitudinal strip on completing winding of a helically wound spool. The perforated line represents a pre-tear line to break the continuity of the longitudinal strip. Tearing along the perforated line is carried out by pulling on the longitudinal strip. The publication mentioned above does not describe means for starting the next winding operation on the new winding core.
There is thus a need to improve the machines for the formation of spools of web material, for example, but not restricted to helical winding spooling machines, as regards severing of the longitudinal strip on completing the winding of one spool and starting the winding of the next spool.